Summary of Work: This project focuses on the innovative application of statistical methods to analyze data on human illnesses, particularly cancer. Most of our efforts have centered on data from two large national studies. We analyzed data from the first and second National Health and Nutrition Examination Surveys (NHANES) to estimate the prevalence of pleural thickening, which is correlated with various adverse health consequences, including lung cancer. Also, we are beginning an analysis of data from the Surveillance, Epidemiology, and End Results (SEER) study, with a goal of summarizing trends in cancer incidence and mortality, using the most recently published information (1973-1994). Based on chest x-rays from the NHANES I (1971-1975) and NHANES II (1976- 1980) studies, we estimated the prevalence in the US of radiographically detectable, dust-related pleural thickening. This pleural thickening is a marker of asbestos exposure, as well as being correlated with excess mortality and increased risk of lung cancer. In the five years between studies, the prevalence estimates for persons aged 35-74 rose from 1.2% to 1.7% for females, 4.5% to 6.4% for males, and 2.8% to 3.9% overall, although the standard errors are large enough to suggest that the observed increases may not be real. Consequently, some chest films from each of the two studies were re-examined by a single reader. The results of these new readings, and their relationship to the old readings, are being analyzed. Several years ago, we analyzed the SEER data for the years 1973-1987 to assess whether aging of the population and patterns of smoking could explain all of the observed increases in cancer incidence. Our age- adjusted analysis showed that not all of the increases could be explained by smoking alone. The current SEER public-use data span the years 1973- 1994 and thus include an additional 7 years of information. We intend to perform a similar analysis, but presently we are still in the planning stages. The results of this new analysis should provide sufficient evidence to support (or contradict) our original findings.